The existence of a specific GHB receptor was predicted by observing the action of GHB and related compounds that primarily act on GABAB receptors, but also exhibit a range of effects which were found not to be produced by GABAB activity, and so were suspected of being produced by a novel and at the time unidentified receptor target. Following the discovery of the "orphan" G-protein coupled receptor GPR172A, it was subsequently found to be the GHB receptor whose existence had been previously predicted. The rat GHB receptor was first cloned and characterised in 2003 followed by the human receptor in 2007.
The function of the GHB receptor appears to be quite different from that of the GABAB receptor. It shares no sequence homology with GABAB, and administration of mixed GHBR/GABAB agonists along with a selective GABAB antagonist or selective agonists for the GHB receptor which are not agonists at GABAB, do not produce a sedative effect, instead causing a stimulant effect followed by convulsions at higher doses, thought to be mediated through increased Na+/K+ current and increased release of dopamine and glutamate.
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^Andriamampandry C, Taleb O, Kemmel V, Humbert JP, Aunis D, Maitre M (March 2007). "Cloning and functional characterization of a gamma-hydroxybutyrate receptor identified in the human brain". FASEB J.21 (3): 885–95. doi:10.1096/fj.06-6509com. PMID17197387.
^Castelli MP, Ferraro L, Mocci I, et al. (November 2003). "Selective gamma-hydroxybutyric acid receptor ligands increase extracellular glutamate in the hippocampus, but fail to activate G protein and to produce the sedative/hypnotic effect of gamma-hydroxybutyric acid". J. Neurochem.87 (3): 722–32. doi:10.1046/j.1471-4159.2003.02037.x. PMID14535954.
^Castelli MP (November 2008). "Multi-faceted aspects of gamma-hydroxybutyric Acid: a neurotransmitter, therapeutic agent and drug of abuse". Mini Rev Med Chem8 (12): 1188–202. doi:10.2174/138955708786141025. PMID18855733.